1. Field of the Invention
The present invention relates to a system and method for processing digital video data, and particularly to a system and method for detecting still objects in digital video data.
2. Description of the Related Technology
In digital video systems, a large amount of digital data is typically used for displaying video. However, conventional transmission channels have a limited capacity to transmit data. Thus, various video compression techniques have been employed to transmit digital video data over conventional transmission channels.
Interframe coding is one video compression technique. Referring to FIG. 1A, in interframe coding, video data is generated to have key frames 10 at a frequency of, for example, 24 Hz (24 frames/second). Referring to FIG. 1B, a display device generates interframes 20 interpolated from the key frames 10 and inserts them in between the key frames 10. In the illustrated example, two interframes 20 are inserted between two key frames 10, and thus the display device can display video at a frequency of 72 Hz (72 frames/second) using 24 Hz-video data. In other examples, display devices can display video at various other frequencies.
In generating interframes, motion compensated interpolation (MCI) can be used to further enhance the accuracy of interframe coding. Referring to FIG. 1C, in MCI, a motion trajectory 30 in video data is estimated based on two succeeding key frames 10. In estimating a motion trajectory, a two-dimensional motion vector is used to represent the displacement of a moving object between key frames 10. The motion vector is used to generate interframes 20 to be inserted between the key frames 10.